既然 (jì rán) is a conjunction meaning 'since' or 'given that', used to introduce a known fact or premise that leads logically to a conclusion or action. The character 既 means 'already' or 'having done', and 然 means 'so' or 'thus'; together, they convey the sense of 'since it is already so'. It signals that the clause following it is the reason or basis for what comes next — typically in the main clause.

This word is common in both spoken and written Chinese, especially in explanations, justifications, or polite suggestions. It often appears at the beginning of a sentence or after a comma, followed by a result clause introduced by 就 (jiù), 所以 (suǒyǐ), or even implied. Unlike the English 'since', 既然 almost always carries a tone of logical inevitability or mild persuasion — not merely time reference. It’s frequently used in everyday reasoning: 'Since you’re here, why not stay for dinner?'